Gardening in Maine is a challenge. Encompassing U.S. Department of Agriculture hardiness zones 3 through 5, Maine has winter temperatures of minus 40 and below. That’s too cold for calla lilies (Zantedeschia spp.) to be hardy, so Maine gardeners must grow them as summer annuals or container plants. Callas are native to Africa and grow from rhizomes, not bulbs, and are not true lilies. There are primarily two species of calla lily available to Maine gardeners.
Calla lilies grow well in wet sites.
White calla lilies (Z. aethiopica), also known as Arum lilies, are the most familiar callas, with dark green leaves and large, white, tubular spathes surrounding a central yellow spadix that holds the true flowers. Arum lilies grow 3 feet tall and 2 feet wide, blooming from late spring through mid-summer. Giant White is a large cultivar with 4-foot leaves and flower spikes up to 6 feet in height. Child’s Perfection is a miniature, growing only 18 inches tall. The spathe on Rod’s Red is clear white on the inside and bright red on the outside. Arum lilies tolerate temperatures down to 50 degrees Fahrenheit and are slower to go dormant in the fall than other calla species, making them the best choice for outdoor plantings in Maine. They’re tolerant of boggy soil and thrive next to streams and ponds. To save the rhizomes from year to year, carefully dig the roots in the fall after the foliage withers and store them in a 50 to 60 degree location.
Not all calla lilies are white.
Smaller and more colorful, the calla lily species Z. albomaculata frequently has spotted foliage and brightly colored spathes. There is a white form available; it’s distinguished from Z. aethiopica white callas by the pronounced green-and-white variegation on the leaves. Most varieties grow 12 to 24 inches tall, making them good choices for Maine container gardens. Many recent introductions are hybrids of Z. albomaculata and other species, including Z. aethiopica. Popular cultivars include Black Pearl, with nearly black spathes edged in maroon, the yellow and red striped Flame, and Golden Chalice, a double-spathed, deep yellow cultivar. Crystal Blush has white spathes that fade to pale pink, while Picasso’s white spathes fade to purple. Majestic Red is, as the name suggests, tall and red. Winter care for this type of calla lily is the same as for Arum lilies.
You should be aware that all parts of calla lilies are poisonous. Use this plant with care anywhere small children or animals have access to it. Wear gloves when planting, as the roots are the most toxic part of the plant. Call 911 or your local poison control center if you think any part of the plant has been ingested or if you have a reaction when handling the plant.